Flickr allows free hosting of imagery under a variety of licenses, some free and some non-free. Flickr allows its users to select the license of their choice and to change it at any time, without any logs of the prior copyright status of the image. This means there is no easy way to check whether an image currently marked as non-free was uploaded under a free license. This causes problems for the use of these images on Wikimedia projects.

Commons uses a review process for verifying the copyright status of images uploaded from Flickr, which allows for the verification of freely licensed images by a bot or trusted user (admins and community approved users) and identification of images where the Commons license is different. This method cannot tell if the image was ever freely available.

Some Flickr users may upload images they don't have the rights to, then license those images as free. When Commons users with Flickr accounts do this in an attempt to upload non-free photos to Commons, this is known as Flickr washing. Commons:Questionable Flickr images lists Flickr users and discussions where we have concluded that certain images marked as freely licensed on Flickr are too questionably licensed for Wikimedia Commons.

One problem when checking licenses of images coming from Flickr is some users provide the static link to the image on Flickr, instead of the description page showing the license. That makes the verification very difficult because you have to search Flickr images hoping you'll find the good tag that will lead you to the good image.

Alternatively, use Flinfo and just input the static URL. Flinfo knows how to deal with a wide variety of Flickr URLs. (By the way: it can also retrieve information about images from other repositories, such as Picasa or panoramio.)

What this means for Wikimedia Commons is unclear, and beware that some institutions (such as the Smithsonian Institute’s Right Statement) flatly contradict “No known copyright restrictions”, asserting copyright and “No commercial use”. One must thus be cautious about uploading such images to Wikimedia Commons.

A great way of finding images on Flickr that can be uploaded to Commons is by using their search tools. You can start on a simple search (limited to freely licensed images), then enter a query.

Or, on the Advanced Search screen, check "Only search within Creative Commons-licensed content", "Find content to use commercially", and "Find content to modify, adapt, or build upon". You can also search by specific licenses, such as by-2.0 or by-sa-2.0.

Also the {{Flickr free}} template lets you search for images under either license.

Even of those images with Creative Commons licenses (a small minority), only about 20 % have a Commons-compatible license (brown and yellow sectors, see image).

If a file on Flickr is not licensed under CC-BY (Attribution) or CC-BY-SA (Attribution and Share Alike), it is usually not allowed on Commons. However, because a copyright holder can change the license of their work, asking them to release their image under a Commons-compatible license is a possibility. Such requests are best made by sending a mail to the Flickr user from within the Flickr website. You will need a Yahoo! account to do this (as Flickr is part of Yahoo!). For more help, see Commons:Flickr files/Appeal for license change.

It is possible that the license of a CC-BY(-SA) image may be changed on Flickr after it has been uploaded to Commons and verified. Flickr users are allowed to change the licenses of their works. It is important to note, though, that once a work has been made available under a given license, the copyright holder cannot legally change or revoke the license on copies of that work. Thus, an image originally licensed as CC-BY and uploaded to Commons under that license (and verified), but later changed on Flickr to All Rights Reserved, may remain on Commons under the CC-BY license. Such a situation is undesirable, of course, and politely asking the Flickr user to reconsider may be a good idea. In the meantime, you may tag the file with {{Flickr-change-of-license}} to indicate the license disparity.

If a Flickr user changes their work's license to a freer version (e.g. CC-BY-SA to CC-BY), the copy on Commons may be updated to use this new license. Simply remove the existing Flickr review template and request a new review with {{Flickrreview}}. As above, however, if the Flickr user changes the license to a less-free version (e.g. CC-BY to CC-BY-SA), Commons is not required to match this as the freer license is not revocable.

Use the Flinfo tool for providing an already filled out version of Template:Information for a picture at Flickr. Input the image ID, or the full URL of a Flickr image. Flinfo can also handle static Flickr URLs.

It would be polite and collegial to leave a comment on the image's Flickr page stating that it was uploaded to Commons. If the user has disabled commenting, consider sending them a message via FlickrMail instead.

If an image is only available at a low resolution, the user may retain original-resolution photos on their local disk, so in addition to uploading a low-resolution version, contact them to ask if they can send you higher-resolution photos.

Flickr now allows video files to be uploaded. However, these cannot currently be transferred easily like photos can. To get an uploadable copy of the video you can either download it or ask the uploader to provide you with a copy (e. g., by email). To download them, use the Flickr api explorer. Enter the id of the video (the number in the url). In the result look for "Site MP4" and download the url in the "source" field. Because these files are in MP4 format which is not accepted on Commons, they must first be converted before upload is possible (see help:converting video for options).